Condenser-type bushing.



.|- E. MATEER & H. G. NIACNALD.

coNnENsEn TYPE BusmNG.

APPLICAHON FILED JUNE 8.1917. 1,264,1 13. Patented Apr. 23,1918.

ATTORNEY WITNESSES:

UNITED STATES PATENT OFFICE.

JESSE E. MATEER, OF WILKINSBURG, AND HOWARD Gr. MACDONALD, 0F MURRAYSVILLE, PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA.

CONDENSER-TYPE BUSHING.

Specification of Letters Patent.

Patented Apr. 23, 1918.

Application led J'une 8, 1917. Serial No. 173,459.

' lators, and it has for its object to provide an insulator that may be economically manu-l In this form, theA conducting layers termi-' nated in superposed horizontal pla nes, as did also the adjacent insulating layers which imparted mechanical support to such conducting layers.

In constructing a bushing of this character, the rough bushing, which tapers in both directions from its central portion, is removed, with its mandrel, from the machine in which it is formed and is laced in a lathe in order that its end portions may be properly tapered in the form of a series of steps. In its rough form, the bushing comprises conducting layers of different ,lengths and immediately adjacent insulating convolutions the ends of which are in proximity to the ends of conducting layers. As a consequence, it is necessary to machine both ends of the bushing subsequent to its being removed from the winding machine. The machining of the bushing is a delicate process and requires considerable skill on. the part of the operator.

After the machined bushing is removed from the lathe, it is sometimes necessary to seal a hollow cylindrical extension over the exposed tapered end of the bushing in order to exclude air and moisture from the body portions thereof when the bushing is to be employed out-of-doors or is to be subjected to other adverse conditions. This form of bushing, as it is commercially employed, is illustrated and described in the U. S. Patent to J. E. Matser No. 1,129,500.

By means of the present invention, we'

provide a condenser-type bushing in which tapered insulating layers, as heretofore employed, are dispensed with, while the concentric conducting layers of various lengths terminate at the proper points along the longitudinal axis of the bushing and are protected against all deterioration by the exterior and intermediate elongated insulating layers or convolutions. As a consequence of this form of construe tion, the lathe operation may be omitted, since the bushing, of itself, possesses an eX- terior surface that will adequately protect it against deterioration under all ordinary conditions. Of course, when such a bush- .ing is to be installed out-of-doors, it may be advisable to provide a porcelain jacket therefor, as is usual under such conditions, to afford protection against rain.

For a better understanding of the characteristic features of our invention, reference may be had to the following description and the accompanying drawing the single figure of which is a view, partially in section and partially in elevation, of a p0rtion of an insulating bushing embodying a form of our invention.

Referring to the drawing, high-potential conducting leads 2, which are to be insulated by means of the bushing of our invention, are threaded through a central tubular member 3 which, in this instance, is composed of insulating material wound in accordance with the principles set forth in U. S. Ifatent No. 757,385 to Emil Haefely. An ad]acent conducting layer 4, preferably wound in the forni of a continuous convolution of tin foil, is applied to the exterior surface of the inner insulating tube 3. A second insulating layer 5 is wound exteriorly of the conducting layer 4 and isof the same length as the inner insulating layer 3. In a similar manner, a plurality of conducting layers of different lengths alternate in position with a plurality of insulating layers of equal lengths totorm a built-up condenser-type bushing which possesses the same electrical characteristics as 'that shown in lU. S. Patent No. 952,513 to el.. C. Dow.

The lengths of the spaced conducting layers bear such relation to their diameters that their areas are substantially uniform. The interposed insulating layers are generally of the same thickness but are of equal lengths, whereby the built-up bushing possesses a suhlstantially cylindrical configuration throughout its entire length.

In constructing the bushing, the conducting layers may be readily terminated at the proper points when theyare being wound on the winding machine while the convolutions formingdthe insulating layers extend the entire', length of the bushing. Therefore, when the winding operation is complete, the bushing is ready for service without being machined in a lathe, which operation has heretofore been necessary with bushings possessing tapered or stepped ends. It will be observed that the exposed ends of the conducting layers are sealed in by means of the elongated insulating layers. In this manner, the vital parts of the bushing are protected against moisture, air and accumulations of dust. The insulating layers or convolutions, as they come in contact with one another at both ends of the bushing, form a substantially homogeneous insulating body that possesses its greatestthickness at the ends o f the bushing and gradually decreases in thickness toward the central portion of the bushing. The insulating strength of the bushing is thus increased, since the potential at which corona may form at the ends of the conducting layers is greatly increased by reason of the greater dielectric trength of this homogeneous insulating ody.

When the bushing is to be used out-otdoors, where it will be exposed to all weather conditions, it may be advisable to provide it with a plurality of insulating rings 6 having overhanging flanges or petticoats 7. Each of the rings 6 is preferably formed of porcelain or other suitable insulating material and is provided with an annular projection 10 within its lange 7 which closely fits over, and is cemented to, the upper end of the ring next below. Cement 11 is poured into the spaces between the adjacent rings in order to hold them in fixed positions. An insulating gum 12 may, in this instance, be poured around the insulating bushing in the space between the bushing and the inner cylindrical walls provided by the built-up rings 6. A metal cap 13 is provided where- ,by electrical connections may be made be- Langue tween an external circuit and the conductors 2.

It will be understood that modifications of our invention may be made without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. An insulating bushing comprising a plurality of insulating layers of unit'orm length, and interposed conducting layers of different lengths.

2. An insulating bushing comprising' a. plurality of cylindrical insulating convolutions forming layers of uniform length, and interposed cylindrical conducting layers of diiferent lengths.

3. An insulating bushing comprising a plurality of insulating layers that terminate at the same plane adjacent at least one end of the bushing, and interposed conducting layers thatJ severally terminate at different planes on the corresponding bushing end.

4. An insulating bushing comprising a plurality of insulating layers that terminate at the same plane adjacent to at least one end of the bushing, and shorter alternate conducting layers of diiierent lengths.

5. An insulating `bushing comprising a plurality of spaced and substantially concentric conducting layers of different lengths, and exterior and interposed insulating convolutions forming insulating layers of equal lengths.

6. An insulating bushing comprising substantially concentric and alternating conducting and insulating cylinders, the conducting cylinders being of different lengths and the insulating cylinders having equal lengths.

7. An insulating bushing comprising a plurality of spaced substantially concentric metal cylinders, and interposed insulating cylinders, the metal cylinders severally terminating in superposed planes and the insulating layers having equal lengths in order to seal in the ends of said metal cylinders 8. An insulating bushing comprising a plurality of substantially concentric metal cylinders of different lengths, and exterior and interposed insulating convolutions forming layers of equal lengths in order to'provide an external homogeneous insulatin body immediately adjacent to the ends cgi the bushing and of decreasing thickness toward an intermediate portion of the bushin lin testimony whereof, we have hereunto subscribed our names this 23rd day of May,

JESSE E. MATEER. HOWARD G. MACDONALD. 

